Clean human hair quickly returns to its "dirty" condition due to contact with the environment and due to the buildup of the sebum secreted by the head. Within a short time (one day to a few days) hair begins to look and feel "dirty". In modern cultures, this look and feel is considered unacceptable requiring the wearer to shampoo their hair frequently. In some countries, the daily shampooing of hair is considered a normal requirement for proper hygiene, whether or not the hair has actually become "dirty".
Shampooing cleans the hair by the removal of environmental contaminants along with the sebum. However, shampooing removes natural oils and other moisturizing materials. If the hair is of significant length, the hair can be tangled and becomes unmanageable. Once dry, the hair has lost its shine and luster and can be dry and frizzy. Hair can also maintain a static charge when dry that results in "fly-away hair". If a shower is taken at the time of this shampooing, the natural oils etc. are also removed from the skin and nails.
As this hair problem has surfaced in the modern era, solutions have been developed to correct or to minimize the problem from frequent shampooing. The first acceptable solutions entailed the post-shampoo application of hair conditioners and hair rinses, generally while the hair is still wet immediately after shampooing. These conditioners and rinses were left on the hair for a period of time to allow sufficient treatment and then removed by rinsing with water. These solutions have, as late, been deemed inconvenient and time consuming. The solution to this problem has been the incorporation of conditioners into the shampoo itself, thus the advent of "conditioning shampoo".
Shampoos that contain conditioners or conditioning agents have not been completely satisfactory for various reasons. Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2-4.0. Therefore, at the pH of a typical shampoo (about 5.5-6.5), hair carries a net negative charge. Consequently, cationic polymers due to their positive charge have long been used as conditioners in shampoo formulations, or as a separate treatment, in order to improve the wet and dry combability of the hair. The substantivity of the cationic polymers for negatively charged hair along with film formation facilitates detangling during wet hair combing and a reduction in static flyaway during dry hair combing. Cationic polymers generally also impart softness and suppleness to hair.
When cationic polymers are added to shampoos containing good cleaning anionic surfactants, formation of highly surface active association complexes generally takes place, which imparts improved foam stability to the shampoo but provides poor conditioning. Maximum surface activity and foam stability, or lather, are achieved at near stoichiometric ratios of anionic surfactant: cationic polymer, where the complex is least water soluble. However, cationic conditioners exhibit some incompatibility at these ratios. Compatibility gives a commercially more desirable clear formulation, while incompatibility leads to a haze or precipitation, which is aesthetically less desirable in some formulations. Additionally when cationic surfactants are added as an ingredient in the shampoo, they do not provide optimal overall conditioning to the hair in the area of softness and tend to build up on the hair resulting in an unclean feel.
When various silicones are added to shampoos containing good cleaning anionic surfactants, improved conditioning properties are observed, however the silicones tend to build up on the hair after repeated shampoo application causing the hair to take on a greasy, unclean appearance.
Combinations of silicones and cationic polymers have been disclosed in an attempt to remedy the above mentioned shortcomings, but they fall short of delivering optimal conditioning properties while maintaining hair in a clean, ungreasy appearance after repeated shampoo applications.
Polyampholyte conditioning polymers have been disclosed that provide excellent wet conditioning properties, but these materials do not deliver the desired soft, shiny appearance to dry hair.
In spite of these attempts to provide optimal combinations of cleaning ability and hair conditioning, it remains desirable to provide further improved hair conditioning shampoo compositions. For instance, it remains desirable to improve overall conditioning, and especially shine and luster, wet and dry combing, and dry hair feel, of hair treated with shampoo containing conditioning materials. For shampoos containing oily materials in combination with cationic materials, it remains desirable to improve overall conditioning:, especially wet combing and detangling, dry combing, and dry hair feel. However merely increasing the level of one or both conditioning ingredients can result in adverse effects such as greasy hair feel and loss of fullness. It is desirable to improve conditioning without suffering from these drawbacks.
It is desirable to provide shampoo compositions and methods for cleaning and conditioning hair which can provide excellent cleaning performance and improved levels of conditioning while minimizing any adverse side effects associated with build-up due to the use of excess conditioning agent.
In addition to the above, the surface properties of human skin and nails are, of course, of basic interest in cosmetic science, and there has thus been a long-standing desire to discover compositions which will beneficially affect the topical condition of this keratinous substrate. Skin conditioning products are desired which will function to improve such properties as retention of skin moisture, softening of the skin, attraction of air moisture, retardation of skin water loss, reduction of fine lines and wrinkles, feel and reduction of skin irritations caused by contact with detergents, soaps and the like.
A desirable skin conditioner should impart all or some of the attributes of an emollient and a humectant, as well as provide improved lubricity and feel to the skin after treatment and/or reduce skin irritation caused by other components in the products such as soaps, detergents, foam boosters, surfactants, perfumes and the like.
There is an ongoing need to find new products for treating skin and nails that provide combinations of the above benefits.